1. Field of the Invention
The present invention relates to a display apparatus, a method of manufacturing the display apparatus, and an electronic apparatus, and more particularly, to a display apparatus in which pixels including an electro-optic element are arranged two-dimensionally in a matrix form, a method of manufacturing the display apparatus, and an electronic apparatus including the display apparatus.
2. Description of the Related Art
In recent years, in the field of display apparatuses displaying an image, flat type display apparatuses in which pixels (pixel circuits) are arranged in a matrix form have rapidly come into wide use. As one of the flat type display apparatuses, there is known a display apparatus in which a so-called current-driven-type electro-optic element, in which light emission luminance varies according to the value of current flowing in a device, is used as a light-emitting element. As the current-driven-type electro-optic element, there is known an organic EL element which uses the phenomenon in which light is emitted when an electric field is applied to the organic thin film using electro-luminescence (EL) of an organic material.
An organic EL display apparatus using the organic EL element as a light-emitting element of the pixel has the following features. That is, the organic EL element consumes less power since the organic EL element can be driven with an applied voltage of 10 V or less. The organic EL element has high image visibility compared to a liquid crystal display apparatus, since the organic EL element is a self-luminous element. Moreover, since an illumination member such as a backlight member is not necessary, lightness and thinness can be realized easily. Furthermore, since the organic EL element has a high response speed of about several μsec, afterimages rarely occur when a video is displayed.
As a driving method of the organic EL display apparatus, there are a simple (passive) matrix type and an active matrix type, like a liquid crystal display apparatus. The simple matrix type display apparatus has a simple configuration. However, a problem may arise in that it is difficult to realize a large-scale and high precision display apparatus since a light emission period of an electro-optic element becomes shorter with an increase in the number of scanning lines (that is, the number of pixels).
Therefore, in recent years, an active matrix type display apparatus has actively been developed in which current flowing in an electro-optic element is controlled by an active element disposed in the same pixel together with the electro-optic element, for example, by an insulation gate type electric field effect transistor. In general, a TFT (Thin Film Transistor) is used as the insulation gate type electric field effect transistor. It is easy to realize a large-scale and high precision active matrix type display apparatus since the electro-optic element continues emitting light during a period of one display frame.
A pixel circuit driven according to an active matrix type and including the current-driven-type electro-optic element includes a driving circuit driving the electro-optic element in addition to the electro-optic element. As the driving circuit, there is known a pixel circuit including the organic El element 21, which is a current-driven-type electro-optic element, a driving transistor 22, a writing transistor 23, and a holding capacitor 24 (for example, see Japanese Unexamined Patent Application Publication No. 2008-310127).
Japanese Unexamined Patent Application Publication No. 2008-310127 discloses a so-called bootstrap operation of varying a gate potential Vg in association with a source potential Vs of the driving transistor 22 when a gate electrode of the driving transistor 22 is in a floating state (see paragraph 0071 of Japanese Unexamined Patent Application Publication No. 2008-310127). According to Japanese Unexamined Patent Application Publication No. 2008-310127, a gate-source voltage Vgs of the driving transistor 22 is maintained constantly even when an I-V characteristic of the organic EL element 21 is changed with time due to the bootstrap operation. Therefore, the light emission luminance is maintained constantly (see paragraph 0093 of Japanese Unexamined Patent Application Publication No. 2008-310127).